Study On The Degradation Effect Of Aspergillus Niger Strains YF1 To Nicosulfuron

The sulfonylurea herbicide nicosulfuron is the most widely used type of herbicide in corn fields.Due to the extensive use of the herbicide,the problem of pesticide residues in the field has become increasingly prominent,and has posed a great phytotoxicity problems on the post-crop.The use of microbial remediation technology to reduce pesticide residues in the field has become an important means of contaminated soil remediation.In this study,we research the application of the nicrosulfuron-degrading strain YF1?Aspergillus niger?and its extracellular enzymes based on previous experiments.The study was as follows:?1?using single factor experiment method to test the initial pH and culture time of YF1 solid fermentation.The results showed that the initial pH of YF1 solid fermentation was 7.5,and the optimum incubation time was 144 h.?2?Degradation effect of YF1 bacteria.Through screening for the sensitive paints of nicosulfuron,chooseing wheat as the most suitable sensitive plant for the follow-up studies.The mainly sensitive part of wheat to nicosulfuron was the above-ground,so the height of wheat was the main measurement index,and measured the IC₅₀ of nicosulfuron to the height of wheat was 0.051 mg/kg.The indoor test results show that:When the concentration of nicosulfuron in the soil was 0.1 mg/kg,adding 25 g of bactericide for 42 d could reduce the inhibition rate of nicosulfuron on wheat from 70.63%to no obvious phytotoxicity;when the concentration of nicosulfuron in soil was 0.05 mg/kg,adding 12.5 g of bactericide for 35 d could reduce the inhibitory rate of nicosulfuron on wheat from 57.97%to 1.55%;when the concentration of nicosulfuron in soil was 0.025 mg/kg,adding 12.5 g of bactericide for 35 d,could reduce the inhibitory rate of nicosulfuron on wheat from 37.91%to0.79%;and after the application of the fungicides,the fresh weight of wheat could be significantly increased and the growth of wheat could be significantly promoted.?3?Determination of the field degradation effect of YF1 strain bactericide.When the application of 10%nicosulfuron oil suspension in soil was 30 mL/mu,the YF1bactericide can reduce the inhibition rate of nicosulfuron against wheat by about 20%;When the application of 10%nicosulfuron oil suspension in soil is 40 mL/mu,YF1bactericide can reduce the inhibition rate of Nicosulfuron against cabbage by about40%,and can completely relieve the damage of Nicosulfuron to wheat;When the application of 10%nicosulfuron oil suspension in soil was 50 mL/mu,YF1bactericide can reduce the inhibition rate of Nicosulfuron against cabbage by about10%,and can completely relieve the damage of Nicosulfuron to wheat;there was no obvious alleviation of rapeseed.?4?Preparation of the seed coating agents for extracellular enzymes of YF1Strain.The High-performance liquid chromatography was used to screen the inhibitory effect of glucoamylase and?-amylase on the inhibition of nicosulfuron based on the film former and antifreeze agent.Select chitosan as the most suitable film former and propylene glycol was the best antifreeze agent to preparation for seed coating agent.The preparation method was:Prepare a 2%solution of chitosan with 1%acetic acid solution and add 4%propylene glycola of total volume.And preparing glucoamylase and?-amylase into different concentrations with 2%chitosan solution.The seed coating agent was coated with wheat seeds at a ratio of 1:35,finally determine the effect.?5?Determination of the effect of protein seed coating on the degradation of nicosulfuron.Indoor pot experiment results showed that when the concentration of nicosulfuron in the soil was 0.05 mg/kg,The contentration of glucoamylase and?-amylase in protein seed coating can degrade the phytotoxicity of nicosulfuron to no harm that occur on wheat;when the concentration of nicosulfuron in soil was 0.075mg/kg,and the glucoamylase content in seed coating agent is 62.5 mg/kg,which can reduce the inhibition rate of nicosulfuron on wheat from 63.11%to 39.30%.When the content of?-amylase in seed coating agent was 500 mg/kg,the inhibition rate can be reduced from 63.11%to 32.05%;when the concentration of nicosulfuron in soil was0.1 mg/kg,and the contentration of glucoamylase in seed coating agent was 500mg/kg,the inhibition rate of nicosulfuron on wheat was reduced from 69.26%to34.63%.When the content of?-amylase was 500 mg/kg,the inhibition rate could be reduced from 69.26%to 47.50%.